Keratoacanthomas are very characteristic-appearing lesions on the skin that also look very distinctive on histopathology. I get these confused on histopathology with molluscum contagiosum, so I think this is an important condition to know.

Gross Appearance

Keratoacanthomas begin as flesh-colored papules, most commonly on the lower eyelid, that rapidly develops into a dome-shaped nodule with a central keratin-filled crater with elevated and rolled margins.

Over the next 3-6 months, there is typically gradual involution.

Histopathology

Histopathology of a keratoacanthoma. Note the significant keratin-filled crater (pink in the middle).

The histopathologic description for keratoacanthomas is acanthosis (increased thickness of all layers of epithelium except for keratin layer) with hyperkeratosis (increased thickness of keratin layer) and a central keratin crater, often with atypia and mitoses.

Stromal invasion should be considered a well-differentiated squamous cell carcinoma.

Do you have any suggestions on what else might be important to remember about keratoacanthomas that may show up on the OKAP? Do you have any tips for helping to remember all of this information? Do you have any requests for specific topics to cover? Leave a comment or contact us!